Accumulation of space debris is a growing problem in many orbital regimes and poses a hazard to space vehicles. Space debris (also known as “orbital debris,” “space junk,” or “space waste”) includes the collection of objects, such as spent rocket stages, defunct satellites, explosion fragments, and collision fragments, in orbit around Earth which were created by space traffic but no longer serve any useful purpose. This debris poses a potential collision risk for operational space vehicles because the orbits of the debris often overlap with the trajectories of spacecraft. The risk of collision is increased in the low earth orbit (LEO), partly due to the combined effect of high operational traffic in the LEO, and the natural slow gravitational decay process which brings near-orbit debris “home” to the LEO.
Scientists have explored a number of techniques to clear debris from space, among them natural decay, debris grabbers, transfer to a dump orbit, and space sweepers. Natural gravitational decay takes a long time to decrease the orbital velocity of debris to the point of re-entry and is ineffective in the face of rapid build-up. Debris grabbers, which typically involve using a tethered grappling unit having robotic arms to envelop and retrieve target debris, require tremendous fuel consumption and also require the development of sensor systems to detect and trace debris. Transferring to a dump orbit raises difficult questions about appropriate dump sites. Other methods, involving use of tethers to bleed energy through induced currents, aero shields, or using an aerogel of compressed gas from cylinders to provide a retrograde drag, are inadequate because they are highly energy-intensive and require the lofting of mass into an orbit aligned with the targeted space debris.